The results suggest that the relationship between \(\mathrm {SDR_{inp}}\)  and SI-SDR is approximately linear. A-SPADE is the only exception, since for low \(\mathrm {SDR_{inp}}\)  values (i.e., for highly distorted inputs) the performance drops significantly (left side of Figure REF ).
This performance decrease has been reported previously in the literature for various declipping algorithms [1]}, [2]}.
At the same time, we see all models decrease the SI-SDR improvement for high \(\mathrm {SDR_{inp}}\)  (i.e., right side of Figure REF ): since the input signal presents low distortion, there is also less margin for improvement.
